Some bangles used as accessories worn on the wrist, arm or ankle, for example, are formed as C-shaped annuluses provided at one portion with an end gap to make them smaller, lighter and easier to put on and take off than traditional ring-shaped bangles made of metal or the like. For still easier wearing, substantially annular-shaped accessories have been developed that interconnect multiple structural elements to form a substantially annular body having ends and enable diameter expansion by internally inserting a core made of a slender metal sheet, wire or similar.
Conventional expandable C-shaped annular accessories have the opposite ends of a C-shaped member, made of shape-memory alloy, for example, connected either by applying a conventional connecting method such as welding to one or another internal end of the substantially annular-shaped accessory or by engaging with a locking member. A diameter-expanding force applied when enlarging the diameter of the substantially annular accessory for putting it on an arm, for instance, fully acts on the opposite end engaging regions, so that a problem arises of the opposite end engaging regions easily breaking. Moreover, the small expandability range of the conventional structure raises a problem of the accessory being hard to put on.
Further, with a conventional substantially annular-shaped accessory made of simple cuboid structural elements, the end faces that are the mating surfaces between the structural elements come into contact during diameter enlargement, so that damage by contact during diameter enlargement with ornaments (e.g., diamonds) in the vicinity of the structural element surface ends becomes an issue. Moreover, in the case of a substantially annular-shaped accessory whose structural elements are simple cuboids, the surface ends come into full area contact during diameter enlargement, which is a problem because the resulting large resistance degrades ease of diameter enlargement and makes the accessory harder to put on and take off.
In the case of the conventional substantially annular-shaped accessory made of multiple structural elements of simple cuboid shape, a problem has been observed of the accessory's all-important appearance being spoiled by individual structural elements being laterally shifted under external pressure in the worn condition. Although substantially annular-shaped accessories incorporating a complicated internal structure for preventing lateral shifting have been developed, they are disadvantageous in the points of involving more production processes, higher die cost, and structural complexity.
As accessories are by nature worn for decoration, their design is of utmost importance and a major design factor particularly for accessories embellished with finely cut jewels is the angle of light incidence. In the case of the most common 58-facet brilliant-cut diamond that emerged from calculation of refraction index etc. for maximizing diamond brilliance, light incident from above reflects from every internal surface to shine out from the top, and this brilliance is considered to be the very essence of what the purchaser wants. With the aim of ensuring entry of light from various angles, cross-sectionally hemispheric bangles, rings and other products featuring diamonds or the like on the surface have been developed, but a need is still felt for ones that the user feels comfortable about putting on and taking off and that give a sense of firmness when worn.
The aforesaid accessory of hemispherical cross-sectional shape can elicit gorgeous brilliance from ornaments (such as diamonds) by enabling incidence of light from various angles, but the accessory has a problem of incurring breakage and gem detachment because its entire surface comes into contact with clothing, walls and various other objects. Moreover, the large, strong prongs required to hold a large ornament (such as a diamond) in order to prevent the ornament (such as a diamond) from falling out are apt to catch on clothing and similar, which is also a problem.
A desire has therefore been felt for a substantially annular-shaped accessory whose engaging region does not easily break, whose structural element surface ends do not interfere with ornaments (such as diamonds) during diameter enlargement, whose resistance to diameter enlargement is low, whose structural elements do not experience lateral shifting under pressure from the outside, and which enables ornaments to be set at various angles, can prevent ornaments (such as diamonds) from falling out, and does not require large, strong setting prongs.